174

QUALITY AND SAFETY CONSIDERATIONS FORTHERMALLY PROCESSED BLUE CRAB MEAT

Keith W. Gates, Amanda H. Parker, Diana L. Bauer,Yao-wen Huang, and Thomas E, Rippen3

University of GeorgiaMarine Extension Service

715 Bay StreetBrunswick, GA 31520

University of' GeorgiaDepartment of Food Science and Technology

Athens, GA 30602

VPI and SU Seafood Experiment Station102 S. King Street

Hampton, VA 23669

INTRODUCTION

Blue crabs comprise the largest crab fishery in the United States. U.S. landings in 1991were 89.9 million kg �22.1 million lb!, with a dock value of $73.3 million 9!. Much of that supplywas commercially cooked and marketed as fresh or pasteurized product. Crab meat is highlyperishable and can serve as the vector for several serious food pathogens. Every crab plant mustestablish an effective quality control program.

Thermal processing requirements must be understood and made an integral part of anyblue crab processing quality control program. The National Marine Fisheries Service NMFS! incooperation with the National Fisheries Institute NFI! has developed a Hazard Analysis CriticalControl Point HACCP! quality control and inspection model for the blue crab industry, Four ofseven critical control points listed by the model involve thermal processing steps or producttemperature control �4!.

In 1984, The National Blue Crab Industry Association NBCIA! adopted thermalprocessing guidelines for the blue crab industry. NBCIA in cooperation with FDA and the stateSea Grant Advisory Programs is upgrading the guidelines to reflect HACCP principles, newprocessing and packaging technologies, and emerging threats from newly uncovered pathogens andspoilage organisms. Although NBCIA has delineated minimum pasteurization requirements interms of calculated F-values, individual processing needs can result in adjusted cooking times andtemperatures to achieve a given shelf life, reduce bluing, or process in newly available packaging�2, 13, 14!,

The University of Georgia Marine Extension Service recently completed a study to evaluatethe effects of several commercially available packaging materials on the quality of pasteurized crabmeat. Stored pasteurized lump meat was held at refrigerated temperatures for 15 mo in the

175

following containers: steel cans, aluminum cans, plastic cans, non-barrier pouches, and barrierpouches �!. Packaging options for pasteurized meat will be discussed later in the paper.

Minimal thermal processing has been proposed as a pre-packaging or post-packagingtreatment to control pathogens in freshly picked crab meat. Blue crab processors through NBCIAhave established the development of proper time/temperature treatments that will destroy Listenamonocytogenes in freshly-picked crab meat as a leading priority,

MATERIALS AND METHODS

The methods followed for the study of commercial container options for the refrigeratedstorage of pasteurized crab meat are explained below, Freshly picked meat obtained from acooperating Georgia processor was packed under commercial conditions into experimental andcontrol pasteurization containers for a 15 mo refrigerated storage study. Meat was cooked at 83.3'C�82 F! to a target F'~t-value of approximately 40 min for au treatments. Lump meat waspasteurized in the following: i! 453.6 g �6 oz! in ¹401 steel cans which served as the industrycontrol Steeltin Can Company, Baltimore, MD!; ii! 226.8 g 8 oz! of crab meat in plastic canswith aluminum easy-open ends ¹307 copolymer polyethylene cans with 283,5 g �0 oz! capacity,King Plastic Corporation, Orange, CA!; iii! 226.8 g 8 oz! in ¹307 aluminum cans Central StatesCan Company, Massillon, OH!; iv! 226.8 g 8 oz! in non-barrier pouches F640 with nylon baseand low density polyethylene sealant, 16.5 cm x 22,9 cm, Cryovac Corporation, Duncan, SC!; and v! 226.8 g 8 oz! in barrier pouches Cryovac P640B with nylon base, Saran barrier, and lowdensity polyethylene sealant, 16.5 cm x 22,9 cm! �!.

RESULTS AND DISCUSSION

Blue crab thermal processing requirements and critical control points can be illustrated byfollowing the major operational steps found in a typical Southeastern U.S. crab plant. Specificdetails may vary from plant to plant, but the general process is the same.

Crabs are commonly harvested by traps and brought to the processing plant the sameafternoon, Live crabs should be cooked within 1 - 2i/2 h of delivery or transferred to coolers, Livecrabs that must be cooked the following day should be refrigerated at between 7.2 C �5 F! and10 C �0 F!. Minimum time/temperature cooking requirements must be met. To prevent crosscontamination, cooked and raw crabs should not be stored in the same cooler �2, 13, 14!.

Crabs are normally cooked by pressurized steam or boiled in water, Achieving propertime/temperature cooks for live crabs is the first critical control point in the NMFS model HACCPprogram, The dominant method is steam retorting at 1.03 bar �5 psi!. Crabs are cooked for 10min after the retort reaches 121.1 C �50 F!. Boiled crabs are usually cooked for 15 min after thewater resumes boiling, Ulmer �9! found that a 15 min boil produced bacterial levels comparableto 10 min of steam retorting, Internal temperatures of steamed crabs usually range from 90.5't�95 F! to 100 C �12F!. Boiled crabs yield more meat because of their higher moisture content,but they have a shorter shelf life �2, 13, 14, 18, 19!.

Retorting criteria are not uniform throughout the United States, but usually require theinternal temperature of the crab to reach between 112.8 C�35 F! and 115,5 C �40 F!. In 1964Ulmer �9! determined the average internal temperature of steamed crabs reached 119.4'C �47F! after 10 min. A record of time/temperature conditions achieved during retorting of each batchof crabs should be maintained by the plant management. Crabs are cooled for several hours aftercooking. NBCIA recommendations require cooked crabs to be refrigerated at c4,4 C �0 F!.Along the Georgia and Gulf Coasts, crab backs are removed and the claws and cores are placedin refrigerated storage at between 0.6 C and 4.4 C �3 F to40 F! before picking, The crabs are

176

Crab meat is removed or picked by hand in most operations, Several grades of white meatbased on meat size are marketed. Market grades include: Jumbo, Lump, and Special. Claw meatand cocktail claws are also picked by hand �0!. Some plants use a Quik-Pik machine CraneResearch and engineering, Hampton, VA! to remove white meat. Crab cores are placed on metalracks and pre-warmed. The meat is shaken onto a belt by the rapidly vibrating machine. OnlySpecial meat is recovered. The Harris Machine uses a hammer mill and salt brine flotation toseparate claws from claw meat. The picking room is included by the second critical control point.Good sanitation methods must be maintained for both hand and machine picked meat. Fresh meatshould be inspected, weighed, packaged, and iced without delay to complete the third critical controlpoint of the crab processing operation. Fresh meat has a shelf life of 6 to 14 d. The shelf life ofrefrigerated crab meat can be extended to 6 mo or more by pasteurization. The product maintainsthe characteristics of fresh crab meat �0, 12, 13, 14, 18!.

The fourth critical control point is confirmation that the pasteurization container ishermetically sealed. The traditional process would inspect the can seam of a 16-ounce steel can.Current pasteurization container options include aluminum cans, plastic pouches, and plastic cans�2, 13, 14!.

NBCIA recommends that the following information be displayed on each container ofpasteurized crab meat:

a code indicating the day, month, and year of processingthe words "PASTEURIZED CRAB MEAT" should appear onboth the individual and shipping containersthe word "Pasteurized" should appear with each use of the words"Crab Meat"

"Perishable-Keep Under Refrigeration" should be prominentlydisplayed on each can

�!�!

�!

�!

At least one individual should be trained to complete can seam or container seal evaluationsand in the adjustment of the seaming/sealing equipment. The plant manager should keep seamor seal records for at least 2 years �2!.

Use of safe and approved time/teinperature parameters for the pasteurization processcomprise the fifth critical control point.

Ciostridiurri botulirntm has traditionally been the organism of concern for canned orother hermetically sealed foods. Thermal process requirements are usually designed arounda target organism, Blue crab pasteurization requirements were developed empirically to achievea desired refrigerated shelf life with no specific target organism. The process was designed toachieve an internal meat temperature of 85'C �85'P! for 1 minute at the geometric center ofa 0.45 kg or 1 lb �01 X 301! steel can. The original empirical process requirements for 1 lbcans have been redefined by thermal lethality or total F-value to expand the concept to othercontainer types and sizes. A z-value of 8.9'C or 16'F was picked arbitrarily in the absence ofa specific target organism. A reference temperature of 85'C or 185'F was chosen. NBCIAadopted a minimum commercial pasteurization process of FM = 31 min for their pasteurizationguidelines. The process provides a wide margin of safety for the destruction of C, boriiliriumType E spores �, 12, 13, 14, 18!. Cockey and Taitro �! estimated that a typical cominercialpasteurization process could provide an 8-D reduction in the number of C. botulirium spores,

picked the following morning, In other states, whole crabs are refrigerated before they are picked�3, 14, 18, 19!,

177

Da5 values determined for Type E spores have ranged from 0.2 - 0.32 min, confirming a 96-Dprocess at F'd = 31 min,

Each pasteurization system should have a time/temperature recording thermometerwith a temperature controller and an indicating thermometer. The system should be calibratedannually.An automaticaHy regulated steam valve is required when steam is used as the heat source forthe pasteurization tank. Baskets, dividers, and cover plates should be perforated to permitcirculation within and around the pasteurization baskets. The water in the bath should bemixed or agitated to achieve a uniform temperature. Compressed air or recirculating pumpsare effective �2!.

The pasteurization process should be standardized by qualified individuals, Subtlevariations in the size and shape of the water bath, steam source, and water circulation patternsmake each processing plant unique. In-plant process standardization and batch monitoring arerequired for any pasteurization operation. Processing boundaries should be set. Any variationin the foHowing parameters would require restandardization of the pasteurization process:

Process time both heating and cooling!Water bath temperatures both heating and cooling!Initial crab meat temperatureContainer size, shape, and material

�!�!�!�!

Rapid cooling of the crab meat is as important to the final quality, safety, and shelf life of theproduct as the heating portion of the pasteurization process. Slow cooling rates may allowinjured bacteria to recover and multiply before refrigeration temperatures are reached withinthe can �, 17, 20!,

The sixth critical control point requires cans to remain in an ice-water bath capable ofcooling the meat at the geometric center of the can to 12.8 C �5 F! within 180 min. Coolingwater should be break-point chlorinated or treated with another acceptable sanitizer. Thecooled meat should be moved to refrigerated storage that is maintained between 0 C �2 F!and 2.2 C �6 F!, The geometric centers of the cans must cool to 2.2 C �6 F! within 18 hor less �2, 14, 17, 18!.

The seventh critical control point addresses storage temperatures. Pasteurized crabineat inust be kept between 0 C �2 F! and 2,2 C �6 F! throughout the wholesale/retaildistribution system. Cooling below 2.2 C �6 F! is important for both maximum shelf life andsafety. C. borulinum does not produce toxin below that temperature, Accidental freezing willtoughen the meat and cause drip and flavor loss. The plant manager should maintain heatingand cooling records covering each batch of pasteurized meat that is processed by the crab plant.Storage teinperatures should be monitored and documented throughout the wholesale and retaildistribution chain �2, 13, 14, 18!.

One potential problem is variation in meat temperature before pasteurization. Oftencrab meat is packed into pasteurization cans directly from the picking table, at temperaturesapproaching 21 C �0 F!, At other times meat inay be placed in cans and held overnight inthe cooler before pasteurization. A process based on an initial meat temperature of 21 C �0F! would under process meat with a starting temperature of 0 C �2 F! or 1 C �3,8 F!.We recoinmend that the pasteurization process be standardized with meat at the lowest initialtemperatures that are expected in the plant, This method is fail-safe. A second approachwould be to measure the initial meat temperature of each batch and adjust the process timeaccordingly �7!.

178

Moody ll! developed a hardware and software system that utilizes a personalcomputer and a Strawberry Tree Strawberry Tree Incorporated, Sunnyvale, CA! dataacquisition board to calculate F-values in real time for each batch of pasteurized meat. Thesystem will allow processors to adjust process times and temperatures to daily changes in meatquality, bacterial loads, starting temperatures, and package types.

Many processors exceed the minimum F'~F-value level of 31 min recommended byNBCIA. Rippen of VPI has compiled industry data that associates achieved lethalities withcommercial shelf life Table 1! �6!, Some processors routinely reach F-values of 60 to 120min.

Table 1. Achieved F'eE values and estimated commercial shelf life of pasteurized blue crabmeat �6!.

Shelf Life

Months!FM-Value

Minutes!

1.510 - 15

15 - 20

20 - 25

25 - 30

30 - 40

2-4

4-6

6-9

9 - 18

12 - 36

Rippen's study determined what shelf life range should be expected for a given pasteurizationFM-value if can seam integrity and proper cooling schedules are maintained. Crab plantowners can tailor processing parameters to meet their marketing needs.

Pasteurized meat spoilage has been at much higher than normal levels over the last 3years. Most of the problems have been traced to poor can seams, however a more insidiousproblem has presented itself. Webster et al, �3! at VPI & SU have uncovered a thermoduric,psychrotrophic, anaerobic, non-pathogenic Clostridium that has been connected with earlyspoilage of pasteurized crab meat, Preliminary data indicates a Da5value of 9 min comparedto 0.2 - 0.32 min for C. boridinum Type E. Fortunately the new isolate does not appear to bewidely distributed. Its true impact on the crab industry is not known.

Heat processing to a F-value of sufficient lethality can provide a safe product withacceptable microbiological shelf life. However, there are other quality factors associated withblue crab meat thermal processing, Pasteurized crab meat can turn blue, Crab blood, copper-based hemocyanin, may form light grey to blue-black complexes. The discoloration is harmless,but it is not aesthetically pleasing �!. Bluing greatly reduces the meat's marketability andvalue. Bluing occurs during pasteurization and intensifies with storage. Bluing is temperaturedependent. Meat processed above 88 C �90 F! frequently discolors. Previous studies have

/shown that pasteurization temperatures between 79.4 C �75 F! and 85 C �85 F! havereduced the incidence of bluing. Pasteurization at 83.3 C �82 F! to achieve a F-value ofapproximately 36 min and storage at -0.5 C to 0 C �1 F - 32 F! has reduced bluing levelsin meat at two cooperating Georgia plants, A temperature of 83.3 C was chosen as acompromise between anticipated bluing reduction and the practical need for processors to limitincreased cooking times required for lower pasteurization temperatures. Contamination ofpicked meat with metals, particularly iron, accelerates and intensifies bluing, The addition of

179

Reducing free liquid formation by steaming raw crabs and notwashing or fluming cooked crabs.Maintaining an even circulation pattern in the pasteurization tanks.Turbulence in one area of the tank may trigger bluing.Reducing meat contact with any source of iron, including corrodedsteel and aluminum.Trying different package types, styles, and manufacturers until themost satisfactory container is found,

�!

�!

�!

Product dryness is usually caused by cooking longer than 2 h. Dryness is not sensitiveto process temperature. Dryness develops between the meat and the can's headspace, Periodicinversion of the cans during storage can help the problem. Rapid heating and cooling reducesdrying,

Moody �1! has traced the presence of small crystalline grains that are sometimesfound in pasteurized crab meat to struvite, a form of magnesium ammonium phosphate. Theaddition of sodium acid pyrophosphate can control the problem.

Thermal processing can be used as a final treatment for "Fresh Crab Meat".Vegetative cells of pathogenic or spoilage organisms can be targeted, Plate counts can bereduced to achieve market specifications or extend shelf life in packaging that is nothermetically sealed. A specific pathogen such as Lisreria monocytogenes, with a zero tolerancelevel enforced by FDA, can be controlled with steam or microwave heating. Greater consumerawareness has led to increased pressure to deliver pathogen free crab meat. A process tocontrol Lisreria monocyiogenes would need to meet the following criteria, an average Rk:l value>1.0 second with a minimum value of 0,5 seconds 8, 15!.

Gates et al, �! conducted a 15 mo refrigerated storage study to determine the storagecharacteristics of the foHowing previously described pasteurization containers: i! steel cans, ii!polyethylene cans, iii! aluminum cans, iv! non-barrier pouches, and v! barrier pouches.Figures 1, 2, and 3 present heating and cooling rates for the cans. Figure 4 shows the heatingand cooling curves for the pouches. Total heating times and mean F-values obtained for eachtype of container are shown in Table 2. Notice that the process times and shapes of the curvesvary with each package type.

and phosphates can retard or reduce bluing levels �, 5, 21, 22!, Additional quality controlsteps that can help control bluing include:

180

CRAB MEAT PASTEURIZATION

34 OZ SIBHL CANS

0 300 300 300

� CAN I CAN I CAN 3 WA11R WAIIR

Figure I, Time/temperature pasteurization curves showing both heating and coolingof crab meat in steel cans,

CIUtB MEAT PASTEURIZATION

~ OZ SIASIIC CANS

CAY 3 . - WAllR WAIIR

Figure 2. Time/temperature pasteurization curves showing both heating and coolingof crab meat in co-polymer polyethylene cans.

181

CRAB MEAT PASTEURIZATION

160

120

I 100 � CAN I -- CAN 2WATIL WA2201

Figure 3. Time/temperature pasteurization curves showing both heating and coolingof crab meat in aluminum cans.

CRAB MEAT PASTEUIGZATION

100

160

120

8 12 100

120

� 0A00100 I SARNSE ~ - - NRLRARRIR 1

Wali WAI00

Figure 4. Time/temperature pasteurization curves showing both heating and coolingof crab meat in barrier and non-barrier pouches,

182

Table 2. Total heating times and achieved F'E-values for steel cans, plastic cans, aluminumcans, non-barrier pouches, and barrier pouches.

Container

TypeCook Time

Minutes!F's'8- V aiue

Minutes!Steel

Plastic

Aluminum

Non-barrier Pouch

Barrier Pouch

Pasteurized meat in plastic containers had higher sensory color and appearance scoresthan meat from other evaluated containers through 8 mo of refrigerated storage, Barrierpouches were the least effective package, scoring below other containers for sensory quality andwhiteness. Microbiological shelf life was limited to 10 mo, Aluminum and plastic containersscored the highest sensory color and appearance ratings at 10 and 13 mo of storage. Meat fromsteel cans was microbiologically and chemically spoiled following 15 mo of storage. Meat inplastic and aluminum cans and non-barrier pouches maintained acceptable sensory andmicrobiological quality through 15 mo. Meat pasteurized in less expensive plastic andaluminum containers had better sensory and microbiological quality than meat packed in steelcans.

CONCLUSIONS

Thermal processing is an integral part of the blue crab industry, Adoption of HACCPquality control procedures, the introduction of new packaging materials, and the use ofcomputer processing technology can provide improved quality and safety for a traditionalseafood industry.

AC KNOWLEDGEMENTS

This research was sponsored in part by the National Oceanic and AtmosphericAdministration Office of Sea Grant under Grant DNA 88AA-D-SG098. The views expressedherein are those of the authors and do not necessarily reflect the views of NOAA or any of itssubagencies. The U.S. Government is authorized to produce and distribute reprints forgovernmental purposes notwithstanding any copyright notation that may appear hereon. Theuse of trade names in this publication does not imply endorsement by the University ofGeorgia, nor criticism of similar ones not mentioned.

REFERENCES

BOON, D. 1975. Discoloration of processed crab meat. A review. J, Food Sci. 40:756-761.

COCKEY, R.R. and T. CHAI. 1991. Microbiology of crustacea processing: crabs. In,"Microbiology of Marine food Products," D.R. Ward and C.R, Hackney, Ed.Van Nostrand Reinhold, New York.

COCKEY R. and M. TAITRO. 1974. Survival studies with spores of Clostridiumbotulinam Type E in pasteurized meat of the blue crab Ca/linectes sapidus.Applied Micro. 27:629.

163

130

120

70

70

53.8

43.8

39,7

45.2

42.8

183

GATES, K.W., J.G. EUDAI.Y, A.H, PARKER, And LA.. PITTMAN, 1984.Microcomputers Improve Quality and Safety for Blue Crab Heat Processing.Georgia Marine Science Center Technical Report Series 84-3, SkidawayIsland, Ga.

GATES, K.W. and A.H. PARKER. 1992. Characterization of minced m e a textracted from blue crab picking plant products. J. Food Sci. 57�67-270 k290.

GATES, K.W., A.H, PARKER, D.L. BAUER, and Y.W. HUANG. 1993, Storagechanges of fresh and pasteurized blue crab meat in different types ofpackaging. J. Food Sci. in press!.

HACKY, C.R., T.E. RIPPEN, and D.R. WARD. 1991. Principles of pasteurizationand minimally processed seafoods, In, "Microbiology of Marine FoodProducts," D.R. Ward and C.R. Hackney, ed. Van Nostrand Reinhold, NewYork.

HARRISON, MA. and Y.W. HUANG, 1990. Thermal death times for Listeriamonocytogenes Scott A! in crab meat. J. Food Prot, 53:878,

HOLLIDAY, M.C. and B.K. O'BANNON. 1992. Fisheries of the United States, 1991,U.S. Department of Commerce, NOAA, National Marine Fisheries Service.Silver Spring, MD.

10. JONES, R.P., M.R. JONES, and W.S. OTWELL. n.d. Seafood Product QualityGuide. Southeastern Fisheries Assoc. Tallahassee, FL.

MOODY, M. 1992. Use of computers to implement HACCP inspection programs inseafood processing plants, Paper presented to SINA and NBCIA CombinedAnnual Convention. Baltimore, MD. Feb. 23-26,

12. NATIONAL BLUE CRAB INDUSTRY ASSOCIATION. 1984. National IndustryPasteurization Standards, National Fisheries Institute. Arlington, VA.

13. NATIONAL FISHERIES INSTITUTE, 1988, Draft Report: Blue Crab HACCPIndustry Workshop, Charleston, SC, June 7-9. National Fisheries InstituteArlington, VA.

NATIONAL MARINE FISHERIES SERVICE. 1990. Model seafood SurveillanceProject - HACCP Model Blue Crab. National Marine Fisheries Service Officeof Trade and Industry Services, Washington, DC.

RIPPEN, T, 1992. Personal communication, VPI and SU Seafood ExperimentStation. Hampton, VA.

16.

RIPPEN, T., C. HACKNEY, and R. LANE. 1989. Factors affecting heat transfer andshelflife of pasteurized crab meat. Proceedings, Interstate Seafood Seminar,Ocean City, MD. Oct. 17-19.

17,

15, REIMERT, J. and C. HACKNEY. 1992. Effective food processing to eliminate L.monocytogenes. Paper presented to Coping with Listeria in the 90'sConference. Baltimore, MD, Feb. 26.

184

19. ULMER, H.B. 1964. Preparation of Chilled Meat from Atlantic Blue Crab. FisheryIndustrial Research. Vol. 2. USDC, Washington, DC.

20. WARD, D.R., G.J. FLICK, C.E. HEBARD, and P.E. TOWNSEND. 1982. ThermalProcessing Pasteurization Manual. VPI-SG-82-04, VPI&SU, Blacksburg, VA.

WATERS, M.E. 1970. Blueing of Processed Crab Meat. I, AStudy of ProcessingProcedures That May Cause a Blue Discoloration in Pasteurized Crab Meat.U.S. Dept. of Commerce. Washington, DC.

21.

WATERS, M.E. 1971. Blueing of Processed Crab Meat. II. Identification of SoineFactors Involved in the Blue Discoloration of Canned Crab Meat Calineciessapidus!. Special Scientific Report Fisheries No. 633. U.S. Department ofCommerce National Marine Fisheries Service. Seattle, WA.

23, WEBSTER, J.B., M,D, PIERSON, and G J. FLICK, 1991. Heat tolerance of spoilageorganisms in pasteurized crab meat. Paper presented to the IFT AnnualMeeting and Food Expo. June 1-5, Dallas, TX.

18. THOMAS, F.B, and S.D. THOMAS, 1974. Technical Operations Manual for the BlueCrab Industry. University of North Carolina Sea Grant Publication UNC-SG-83-02, Raleigh, NC,

185

EXTENDING SHELF LIFE OF FRESH BLUE CRAB NEAT WITH LACTATES

J.R. Haibaum , D.P. Green , L.C. Boyd andW.S. Otwell~

Seafood Laboratory

~ Department of Food ScienceNorth Carolina State University

Raleigh, North Carolina 27695

~ Department of Food Science and Human NutritionUniversity of Florida

Gainesville, Florida 32611

Both real and perceived public health concerns about thequality and safety of seafood products may soon force the seafoodindustry to modify some of its traditional practices. Of specialconcern are previously cooked, ready-to-eat foods such as freshblue crab meat 8!. Early attempts to enhance quality and safetywith additives during processing of fresh �1,13!, frozen �1,22!,canned �! and pasteurized crab meat �7! were either unsuccessful�1,22,17! or not beneficial enough �1,5,13! to be adopted byseafood processors. Consequently, fresh blue crab meat isprimarily sold in the traditional way, which means refrigeratedwith no preservatives added.

In recent years, natural lactic acid and sodium lactate havebeen successfully used in food processing. They are knownantimicrobial agents and provide inhibitory effects on mostpathogens in poultry �4,15,20,6! and red meat �8,1!. Lactatesare recognized as safe GRAS! by the U.S, Food and DrugAdministration FDA! and their use in food processing isrestricted to good manufacturing practices GNP! 9!. Seafoodtechnologists have recently focused their attention on the effectof lactates on shrimp �,4!, fish and frozen crab meat �!.

The primary objective of this study was to demonstrate shelflife extension by lactic acid and sodium lactate in blue crabmeat, and secondly, to determine their effects on physical andsensory qualities.

186

MATERIAL AND METHODS

At]. antic blue crab meat Ca linectes sa idus was purchasedfrom a commercial processor Luther Lewis 6 Son, Davis, NC!. Thecrabs had been pressure cooked, and the meat had been directlypicked into standard one pound plastic containers. The crab meatcontainers were stored in crushed ice and removed only fortreatment and analyses procedures.

Fifty-five pounds of crab meat was mixed under sanitaryconditions to ensure uniformity. It was divided into five equalportions. Control samples were immediately repacked in sanitizedcontainers. Treated samples were dipped for 30 min in either i!water, ii! 1% lactic acid, iii! 4 % sodium lactate or iv! acombination of 1% lactic acid and 4% sodium lactate, They wereallowed to drain for 10 min. The crab meat of all treatments,including the control, was subdivided and stored in separatecontainers for microbiological, physical and sensory analyses. Theexperiment was replicated three times.

~nal~ss

Physical, microbiological and sensory analyses of treatedcrab meat were performed during a 19-day period. Moisture content,pH value, color and texture were measured. Oven moisture and thepH values were determined, using standard procedures �4!. The pHvalues were determined after the treatments. The crab meat �0 g!was blended in distilled water to achieve a final dilution of 1:3 w/v! and the pH was measured, using a Fisher Accumet pH metermodel 620. The texture grades were measured with an Instronuniversal testing machine equipped with a Kramer shear cell. Themaximum force prior to rupture of triplicate 10 g samples wasrecorded. The color of the crab meat was measured with aSpectrogard colorsystem. Measurements, described on the Hunter Labscale, were taken with a tungsten filament and an average daylightsource. The observer angle was 10'. Triplicate 15 g samples wereprepared, and two measurements in different areas were taken.

Aerobic plate count at 35'C and the confirmed test for E.coli were performed, according to standard AOAC procedures �!.

The consumer acceptability of treated crab meat wasevaluated by an in-house consumer panel of 35 panelists on days 1,5 and 8 �6!. Panelists were asked to rank appearance, odor,flavor, texture and overall acceptability. The ratings were givenon a 9 point hedonic scale from dislike extremely '1'! to likeextremely '9'!. All ratings were converted to numerical values.

187

A rating below 5 neither like nor dislike! was considered aconsumer rejection.

RESULTS AND DISCUSSION

Ph sical Parameter

Physical effects of treatments on moisture, pH, color andtexture were analyzed. Control samples had an average moisturecontent of about 76%, Dipping procedures elevated moisture levelsin all samples Figure l!. Water dips resulted in a 5% moistureincrease while all other treatments showed an overall increase ofabout 2%,

The pH value of fresh handpicked crab meat was 7.8 Figure2!. Neither distilled water nor 4% sodium lactate treatments

Figure 1: Oven moisture of fresh blue crab meat following lactatetreatment.

LA = lactic acid, NaL= sodium lactate.

85

83

~ 81

O+ 79'g

77

750 1510

DAYS

TREATMENTS:

CONTROL ~WATER ~1%LA ~4% NaL ~1%LA+4%NaL

Statistical analyses on the means of physical,microbiological and sensory data were performed, using the GLNprocedure �9!. To determine significant differences p�.05!between storage time and treatments, the least-square-means or theWailer-Duncan k-ratio t-test was computed.

188

Figure 2: pH-values of fresh blue crab meat, dippingsolutions and supernatants during lactate treatments.LA = lactic acid, NaL = sodium lactate. combination =

t ALA + 4%NSL.

pH VALUE

9 1 CONTROL WATER 1% LA 4% NaL COMBINAT1ONQsoLUTIoN HBUPERNATART G CRAB HIEAT

affected the pH of the crab meat. The pH of l% lactic acidsolution alone was 2.5 and increased to 4.4 when in combination

with 4% sodium lactate. Both treatments containing lactic acidlowered the resultant meat pH to 6.2.

Visual observations of the crab meat indicated a lighteningin color where lactic acid was used. This was confirmed with

colorimetric measurements using a Hunter color scale. Bothtreatments containing lactic acid had significantly higher Lvalues than the control Figure 3a!. The water and the sodiumlactate dipped samples were lighter than the control, butsignificantly darker than the lactic acid samples. The a-value ofall treated samples shifted to the green spectrum. This colorshift was more pronounced in samples containing sodium lactate intheir treatment solutions Figure 3b!. No significant differenceswere observed measuring the b-value data not shown!.

No significant differences in texture measurements with theInstron universal testing machine were found between lactatesamples and control sample data not shown!.

189

Figure 3: Hunter color L-values AJ and a-values /BJ of fresh blue crab meatfollowing lactate treatments

LA =lactic acid, NaL =sodium lactate, Combo= 1%LA + 4%NaL.

t-j ~ VALUEL VALUE78

1.6

74

0.672

70 0 2 4 8 8 10 12 14 15 58 20 00 2 4 8 8 10 12 14 18 18 20

D AYSDAYS

TREATMENTS

CONTROL ~WATER «1% LA «4% NaL «COMBOTREATMENTS

CONTROL ~ YVATER «1% LA «4% NaL «COMBO

Bacter olo ical ualit

The classification of the crab meat followed similarguidelines described by Gates �2!, Therefore, crab meat sampleswith aerobic plate counts APCs! less than 100,000 cfu/g wereconsidered good quality �0!. Plate counts between 100,000 and1,000,000 cfu/g were classified as acceptable quality. Sampleswith APCs greater than 1,000,000 cfu/g were judged to be spoiled,

The initial quality of the non-treated control sampleaveraged <60,000 cfu/g Figure 4!, with bacterial growth followingthe natural spoilage pattern for fresh crab meat on ice. After alag phase of 5 days, bacterial growth increased slowly. The crabmeat continued to be of good quality until 10 days and wasregarded as unacceptable after 14 days. The microbial quality ofwater-dipped crab meat, one day after treatments indicated that

190

the handling process during treatment did not significantlyincrease the bacterial numbers. Because of the rate of spoilage,good quality shelf life was reduced to 6 days and acceptablequality to 11 days.

Bactericidal properties of the 1% lactic acid solution�,10,15! were demonstrated i! by lowering the initial APCs toless than 10,000 cfu/g and ii! by extending the lag phase to 10

Figure 4: Log of aerobic plate count �5YZJ of fresh bluecrab meat following lactate treatments and storage oncrushed ice.

LA =lactic acid, NaL=sodium lactate

g 6

LL.OU0

5

3 0 10 15 20

DAYS

days. Crab meat remained in good quality <100,000 cfu/g! for 16days and spoiled after 19 days of storage on ice ,000,000cfu/g!. Sodium lactate is known to have a bacteriostatic effect�,20!. Like lactic acid, sodium lactate prolonged the lag phasein blue crab meat to 10 days before bacterial growth commenced.The treatment extended shelf life an average of 20%, to 12 days.The lower spoilage rate was consistent over 15 days but was notfound to be statisticslly significant..

191

The combination of sodium lactate with lactic acid did notoffer an advantage over the sodium lactate treatment in retardingmicrobial spoilage, The spoilage followed a pattern similar to thesodium lactate samples, with a good quality shelf life of 12 days,However, these data were not found to be significantly different p<0.05! from the control.

Once bacterial growth began, growth patterns were similarfor all samples, as indicated by the slope of the curves. Whatadvantage did lactic acid treatment offer? There were two effects,which led to a shelf life extension of 60%, to 16 days. First,initial plate count was reduced and second, the lag phase wasextended. Lactic acid treated crab meat was still in goodcondition <100,000 cfu/g! 2 days after the control samples werespoiled APC,000,000 cfu/g!. The differences were significant ata 0.05 level.

Finally, tests for E. coli in control and treated sampleswere negative during the first 10 days of storage

Sensor Evaluations

All treatments improved the sensory appearance rating ofcrab meat Figure 5a!. This may correlate to the higher moisturecontent and lighter color of the crab meat after the treatments.Differences were more pronounced over time,

A slight off odor was detected by the panel in lactic acidsamples and in the combination samples at the beginning of thestorage time day 1!. This resulted in a lower rating for thistest period Figure 5b!. However, overall odor for all treatments,including the lactic acid containing samples, was not found todiffer significantly p<0.05! from the control. The only exceptionwas the sodium lactate sample, which was preferred by thepanelists.

Panelists accepted the flavor of all samples and rated themabove the rejection level of 5 Figure 6a!. Panelists rated bothtreatments containing lactic acid significantly less than theother treatments. Sodium lactate alone is known to enhance flavor,Panelists found a positive effect on crab flavor and preferredsodium lactate samples over control samples on day 5. Thedifferences in flavor between all samples diminished with storagetime and lost any significance after 8 days.

In terms of sensory texture ratings, no significantdifferences between treatments could be detected by the panelists data not shown!. This confirmed the physical data obtained withthe Instron testing machine.

When asked to judge overall acceptability, panelists ratedboth lactic acid containing treatments lower than the control Figure 6b!. The 4% sodium lactate treatment was judged equal orsuperior to the control p<0,05!.

192

Figure 5: Sensory evaluations of appearance AJ and odor BJ of freshblue crab meat following lactate treatments. Means of the same day

marked with different letters were significantly different at a 0.05 level."JF-value too small.

LA = lactic acid, Nai = sodium lactate, combo= 1%LA + 4%NaL,9= like extremely

1 = dislike extremely BLUE CRAB MEATSENSORY EVALUATIONS

APPEARANCE

HEDONIC SCALE9

A!

DAY 8DAY 1 DAY 5TREATMENTS

EICOkTROL HWATER Q1% LA 034% kaL ERCOMBO

BLUE CRAB MEATSENSORY EVALUATIONS

ODOR

HEDONIC SCALE9

B!

DAY 8DAY 1 DAY 5TR EATMENTS

EI CONTROL EYEWATER E} 1% LA KQ4% ksL H COMBO

193

BLUE CRAB MEATSENSORY EVALUATIONS

FLAVOR

HEDONIC SCALE9

A! 7

DAY 1 DAY 8DAY 5TRKATMEHTS

BCONTROL GWATKR E31% LA 64% NsL 8 COMBO

B LUE C RAB MEATSENSORY EVALUATIONSOVERALL ACCEPTABILITY

HEDONIC SCALE9

B!

DAY 5TREATMENTS

DECONTROL CWATER EI 1% LA 034% NaL EI COMBO

DAY 8

Figure 6: Sensory evaluations of flavor iA! and overall acceptability fB! offresh blue crab meat following lactate treatments. Means of the same daymarked with different letters were significantly different at a 0.05 level. "!F-value too small.

LA= lactic acid, NaL= sodium lactate, combo= f%LA + 4%NaL9= like extremely1 = dislike extremely

194

CONCLUSIONS

Shelf life of fresh blue crab meat was extended 20% bysodium lactate �%!, 60% by lactic acid �%! and 30% by thecombination of both �% lactic acid and 4% sodium lactate!treatments.

Elevated moisture content and an increase in lightness wereobserved in all treated samples. Lactic acid containing treatmentsshowed reduced pH values. No treatment effects on texture weredetectable with either sensory or physical evaluations.

Panelists judged lactate samples better in appearance withno differences found overall in odor and texture, Panelists foundboth lactic acid and sodium lactate treated crab meat to beacceptable with sodium lactate judged best in flavor and overallacceptability.

REFERENCES

ANDERSON, M.E., R.T. MARSHALL and J.S. DICKSON. 1992.Efficacies of acetic, lactic and two mixed acids inreducing numbers of bacteria on surfaces of lean meat.J. Food Safety, 12:139-147.

AOAC. 1984. Official methods of analysis, 14th ed.Association of Official Analytical Chemists,Arlington, Virginia.

APPLEWHITE, L.D., L. RAVELO and W.S. OTWELL. 1991.Measurements of lactate residuals on treated shrimpusing a YSI Lactate analyzer. In: Proc. Sixteenth Ann,Trop. Subtrop. Fish. Tech. Conf. FL Sea Grant Publ. No110, Raleigh, NC.

APPLEWHITE, L.D., W.S. OTWELL and L. RAVELO. 1992. Lactateresiduals in shrimp as a consequence of storage andsodium lactate treatments. In: Proc. Seventeenth Ann.

Trop. Subtrop. Fish. Tech. Conf., FL Sea Grant Publ.,Merida, Mexico.

BABBITT, J.K., D.K. LAW and D.L. CRAWFORD. 1975. Effect ofprecooking on copper content, phenolic content andblueing of canned Dungeness crab meat. J, Food Sci,40�!:649-650.

BACUS, J. and E. BONTENBAL. 1991. Controlling Listeria. Meatand Poultry, June 1991,

BOYD, L.C., D.P. GREEN and L. HENRY. 1991. Application andeffects of lactic acid and cryoprotectants on thestorage stability of frozen crab cores and crab meat.In Proc. Sixteenth Ann. Trop. Subtrop. Fish. Tech.Conf. FL Sea Grant Publ. No 110, Raleigh, NC.

195

8. BUCHANAN, R. L. 1991. Microbiological criteria for cookedready to eat shrimp and crab meat. Food Tech.45�!:157.

CFR. 1977. Current good manufacturing practice inmanufacturing, processing, packing or holding humanfood. Code of Federal regulations, Title 21, Part 110U.S. Govt. Print Office, Washington, D.C.

10. COCKEY, R.R. 1983. Bacteriological standards for freshshellfish and crab meat for selected states and

Canada. UM-SG-NAP-83-01 Cooperative ShellfishAquaculture and Technology Laboratory. Crisfield, ND.

ll. CRAPO, C.A and D.L. CRAWFORD. 1991, Influence ofpolyphosphate soak and cooking procedure on yield andquality of dungeness crab meat. J.. Food Sci.56�!:657-659,664.

12. GATES, K.W., A.H. PARKER, D.L. BAUER and Y. HUANG. 1991.Evaluation of packaging alternatives for fresh andpasteurized crab meat. In' Proc. Sixteenth Ann. Trop.Subtrop. Fish. Tech. Conf. FL Sea Grant Publ. No 110,Raleigh, NC.

13. HANOVER, L.M., N.B. WEBB, A.J. HOWELL and F.B. THONAS. 1973.Effects of cooking and rinsing on protein losses fromblue crabs. J. Milk Food Techn. 36 8!:409-413.

14. IZAT, A.L., M. COLBERG, R.A. THOMAS, M.H. ADAMS and C.D.DRIGGERS. 1990. Effect of lactic acid in processingwaters on the incidence of Salmonella on broilers. J.Food Quality 13:295-306.

15. IZAT, A. L., R. E. HIERHOLZER, J.N. KOPEK, M.H. ADAMS, J. P.NcGINNIS and M.A. REIBER. 1990. The use of propyleneglycpl and/or lactic acid in chill water for reducingsalmonella on broilers. J. Food Proc. Preserv. 14:369-374,

16. LARMOND, E. 1982. Laboratory methods for sensory evaluationsof food, Res. Branch Canada. Dep. Agric,, Ottawa,Canada pp.55-59.

17. LERKE, P, and L. FARBER. 1971. Heat pasteurization of craband shrimp from the Pacific Coast of the UnitedStates: Public health aspects. J. Food Sci. 36�!:277-279.

18. PRASAI, R.K., G.R. ACUFF, L.N. LUCIA, D.S. HALE, J.W. SAVELLand J,B, MORGAN. 1991. Nicrobiological effects of aciddecontamination of beef carcasses at, various locations

in processing. J. Food Prot. 54:868-872.

196

19. SAS INSTITUTE INC. 1985. SAS Users Guide: Statistics,Version 5 Edition. Cary, NC: SAS Institute Inc., 1985.

20. SHELEF, L.A. and Q. YANG. 1992. Growth suppression ofisteria onoc to e es by lactates in broth, chicken

and beef. J. Food. Prot. 54�!:283-287,

21. STRASSER, J. H., J. S. LENNON and F. J. KING. 1971. Bluecrab meat. I. Preservation by freezing. II. Effectof chemical treatments on acceptability, U.S. Dep. ofCommerce, National Oceanic and AtmosphericAdministration, National Marine Fisheries Service,Spec. Scientific Report-Fisheries No. 630:1-26.

22. WEBB, N.B., J.W. TATE, F,B. THOMAS, R.E. CARAWAN and R.J,MONROE. 1976. Effect of freezing, additiwes, andpackaging techniques on the quality of processed bluecrab meat. J. Milk Food Techn. 39�!:345-350.

23. WENTZ, B.A., A.P. DURAN, A. SWARTZENTRUBER, A.H. SCHWAB,F.D. McCLURE, D. ARCHER and R.B. READ, Jr. 1985.Microbiological quality of crab meat duringprocessing. J. Food Prot. 81:44-49.

24. WOYEWODA, A.D., S.J. SHAW, P.J. KE and B.G. BURNS. 1986.Recommended laboratory methods for assessment of fishquality. Canadian Tech. Report Fish. Aquat. Sci., No,1448.

ACKNOWLEDGEMENT S

This research was supported in part by a grant from theNational Coastal Research & Development Institute, the Universityof North Carolina Sea Grant College Program and the North CarolinaCooperative Extension Service. The use of trade names in thispublication does not imply endorsement by North Carolina StateUniversity, nor criticism of ones not mentioned.

197

EXTENDING SHELF LIFE OF REFRIGERATED SEAFOOD PRODUCTS

David P. Green

Seafood LaboratoryDepartment of Food Science

North Carolina State UniversityMorehead City, NC 28557

INTRODUCTION

Seafood products are widely known for their high degree of perishability. For the mostpart, U S, seafood processors have relied on good sanitation and proper time and temperaturecontrols for slowing decomposition and spoilage in refrigerated seafood products, Other foodprocessing industries have employed traditional food preservation concepts for extending shelf lifeof refrigerated foods �9!. These concepts Table 1! include control of water activity ag, pH,irradiation ultraviolet/ionizing!, preservatives and altered atmospheres MAP, CAP or vacuum!.More recently, new technologies such as ohmic heating, ultra high pressure, microwavepasteurization and natural and innovative preservatives have become available to food processors.This paper examines current technologies used in processing blue crab, health regulations impactingthe U.S. blue crab industry and opportunities to apply new technologies for increasing value andextending shelf life of refrigerated blue crab products.

THE U.S. BLUK CRAB PROCESSING INDUSTRY

Current technologies used in processing blue crab involve traditional time and temperaturecontrols and sanitation programs, Cooked, ready-to-eat refrigerated and pasteurized crab meat arethe primary product types. Frozen crab meat has been a traditional type for use in value-addedproducts e.g., crab cakes and deviled crabs!. Market interest in both live and frozen cooked!whole crab, crab portions and vacuum-packed crab meat has increased recently �2!, This interest,coupled with natural fluctuations in blue crab supply, has made for volatile market conditions.

A critical point in the processing of blue crab is cooking. Cooking times, temperatures andmethods affect yield and subsequent shelf life of refrigerated products �,9!. Traditional time andtemperature controls for cooking blue crab were based on industry practice and research during the1950s to 1970s �,20,33!, The products fall under Current Good Manufacturing Practices CGMPs!as required of afl U.S. food processors engaged in interstate commerce �!. Specific time andtemperature controls in production of refrigerated �4,34! and pasteurized �2,21,27! crab meat areavailable,

Still, good sanitation programs are required for the low bacterial levels necessary to protectthe processor from losses due to spoilage and to ensure the safety of the product to the consumer�8,30,31!, During processing, crab meat can be exposed to a wide variety of microorganisms.Therefore, it is vitally important that sanitation programs be rigorously applied, processes carefullymanaged to eliminate cross-contamination and refrigcratcd storage routinely monitored.

198

Table 1. Food Preservation Concepts for Extended Refrigerated Foods

New Technolo ies

Ohmic Heating

Traditional Technolo ies

Water Activity aQ

pH acidity!

Irradiation

Ultra High Pressure

Microwave Pasteurization

Natural Preservatives

Innovative Preservatives

Ultraviolet

Ionizing

Preservatives

Altered Atmosphere

MAP modified!

CAP controlled!

Vacuum

Time and Temperatures

Sanitation prevention!

HEALTH REGULATIONS IMPACTING BLUE CRAB PRODUCTS

All cooked, ready-to-eat blue crab products will be affected by new health regulations,including HACCP-based inspection, microbiological criteria, adulteration and economic fraud andlabeling. Industry along with the U.S, Food and Drug Administration FDA! and the U.S, NationalMarine Fisheries Service NMFS!, has worked cooperatively to implement a Hazard AnalysisCritical Control Point HACCP! inspection program. This approach will improve the quality andsafety of cooked, ready-to-eat blue crab products.

Microbiological criteria Table 4! for cooked, ready-to-eat crab meat and shrimp have beenrecommended for process verification �,25!. They include specific tolerance levels for Salmonella,

Critical steps for control of microbial levels in refrigerated blue crab products are shownin Figure 1. Cooking, picking and packing are identified as critical control points under the bluecrab HACCP regulatory model �6!. Current industry practices for cooking of blue crab includesteam pressure, atmospheric steam partial cook! and boiling Table 2!. Specific process scheduleshave been incorporated into most state health regulations in the United States. Picking and packingrepresent additional critical control points Table 3! where potential bacterial contamination ofproduct is prevented through good manufacturing practices and proper sanitation.

199

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industry. The organism is widespread in nature and the primary concern is for its growth underrefrigerated storage conditions �3,14!. Of significant interest has been detection of Listeria inprocessing plants generally recognized as having better designed sanitation programs, i,e., acleaner working environment �!.

Another issue affecting refrigerated blue crab products is adulteration and economicfraud. Concerns have led U.S, processors to petition the FDA for increased surveillance ofimported products and use of tainper-evident packaging in domestic markets �5!, Thefraudulent mixing of domestic and foreign meats and slacking out of frozen product to be soldas fresh have added to the economic instability of traditional blue crab markets. In an effort tothwart fradulent practices and address health concerns for refrigerated crab products indistribution, North Carolina processors have agreed with state health authorities to use tamper-evident packaging for all North Carolina produced crab products. This new state healthregulation �8! will take effect April 1, 1993,

Another area impacting refrigerated blue crab products is labeling. Historically, use ofthe descriptor "fresh" has referred to cooked blue crab meat that has not undergone any furtherprocessing or freezing. Industry anxiously awaits the FDA's decision on continued use of thisdescriptor for packaging of refrigerated blue crab products. In addition, mandated nutritionlabeling will force blue crab processors to redesign packaging materials and deplete presentstocks of packaging as early as May of 1993.

OPPORTUNITIES FOR NEW PRODUCTS AND NEW MARKETS

Now that we have reviewed current practices and listed challenges facing blue crabprocessors, let's discuss some opportunities for applying new technologies to refrigerated bluecrab products, Broadly speaking, chilled foods are extended shelf life products that exhibit shelflives longer than those traditionally associated with the food and rely mainly on refrigeration forsafety �9!. Examples of extended shelf life products are Oscar Mayer's Lunchables with curedcooked chicken, sodium lactate and MAP, a Contadina pasta that uses A~ MAP and heattreatment after extrusion to destroy psychrophiles and Sara Lee's Bilmar deli meats process thatpackages, pasteurizes and chills without headspace, i.e., sous vide.

What about seafood products? Ionizing irradiation is approved for use in over 30nations to extend shelf life of a variety of foods �0!. Research on seafood products, includingblue crab, has demonstrated positive effects on quality and freshness �1,16,17!. Presently, low-dose gamma irradiation is not approved for use in the U.S, by the FDA in processing ofrefrigerated seafood products. Its approval would greatly enhance the value, safety andconsumer confidence for pathogen-free fresh seafood in the marketplace �0!.

Altered atmospheres are traditional technologies used to extend shelf life of a widevariety of refrigerated foods including fresh fish and shellfish �9!. Its use in the blue crabindustry has been limited primarily to vacuum packaged, frozen hand-picked meats. Currently,MAP does not have U.S. FDA endorsement for seafoods although several European countrieshave accepted this technology for commercial use �!. Limited use of MAP under specifiedconditions was approved under the previous voluntary U.S. NMFS inspection program.

What about extended shelf life blue crab products? Natural and innovativepreservatives represent a new technology so far untapped by traditional seafood processors, Anexample is use of the natural preservative sodium lactate to extend the shelf life of blue crabmeat �2!. Lactates are just one of a variety of GRAS approved substances that may be used asdirect or indirect additives in seafood products,

204

BENEFITS OF INCREASED VALUE AND EXTENDED SHELF LIFE

What are the benefits for industry to incorporate new technologies into currentpractice? Short term benefits are increased value and greater consumer confidence inrefrigerated products. Longer term, the benefits are new forms and markets for extended shelflife products. The blue crab industry traditionally has been a commodity-based industry at themercy of supply and demand economics. Application of new technologies in development ofrefrigerated blue crab products would alleviate restraints on growth and open the door to themodern food era.

Any new development must be properly planned and cautiously scrutinized to ensure itssafety, For industry, this development usually is in cooperation with university and regulatorypersonnel. One approach is the barrier concept which employs a combined technologiesapproach to shelf life extension and safety �3!. Under this approach, all new products shouldbe abuse tested and challenged with various bacteria to check for the effectiveness of the barriersystem. Protocols for verifying the effective control of specific pathogens have been proposed�,8!.

SUMMARY

In summary, regulatory guidelines for processing of cooked, ready-to-eat crab meat arewell defined. The successful implementation of the HACCP-based inspection program for bluecrab will greatly enhance the quality and safety of blue crab products, While the U.S. blue crabindustry is undergoing some significant changes, opportunities do exist for applying innovativeapproaches to extend the shelf life of blue crab products. Establishment of HACCP-basedinspection and microbiological criteria may provide industry with the proper mechanisin to applynew technologies, add value and develop new markets. The challenge before all of us heretoday is to develop a new generation of extended shelf life seafood products.

ACKNOWLEDGEMENTS

This presentation was made possible through the cooperation and support of the UNCSea Grant College Program. The author appreciates the continued program support providedby the NC Cooperative Extension Service and the National Coastal Resources Research andDevelopment Institute. The use of trade names in this publication does not imply endorsementby North Carolina State University, nor criticism of ones not mentioned.

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DICKERSON, R. and M. BERRY, 1976. Heating curves during commercial cookingof the blue crab. J. Milk Food Technol. 39: 258,

DOYLE, M.P. 1991, Evaluating the potential risk from extended shelf life refrigeratedfoods by Clostridium ~tulinum inoculation studies. Food Technology 45:154.

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GRODNER, R.M. and L.S, ANDREWS. 1991. Irradiation. In, "Microbiology of MarineFood Products," ed. D.R. Ward and C.R, Hackney. Van Nostrand Reinhold, NewYork. pp, 429-440.

GRODNER, R.M. and A. HINTON, JR,, 1988. Gamma irradiation of Vibrio choleraiin blue crab ~allinectus ~sa idus!. In, Proc. 11th Tropical and Subtropical FisheriesTechnological Conf., SGR-92. pp. 429-441.

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JOSEPHSON, E,S, and M.S. PETERSON. 1983. Preservation of food by ionizingradiation, CRC Press, Boca Raton, Florida,

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